/Engine/Source/Runtime/CoreUObject/Public/UObject/Object.h
Call Ar.UsingCustomVersion for every CustomVersion that might be serialized by this class when saving. This duplicates CustomVersions declared in Serialize; Serialize still needs to declare them. Used to track which customversions will be used by a package when it is resaved. Not yet exhaustive; add CustomVersions as necessary to remove EditorDomain warnings about missing versions.
static void DeclareCustomVersions ( [FArchive](API\Runtime\Core\Serialization\FArchive) & Ar, const [UClass](API\Runtime\CoreUObject\UObject\UClass) * SpecificSubclass )